The compact disc (CD), video compact disc (VCD) and digital video disc (DVD) are widely used in offices, household and personal information and entertainment. Therefore, the industry has been researching to develop more efficient optical pickup technology to improve the quality of the recording media, such as CD, VCD, and DVD,
An optical pickup reads or writes data on the recording media. In general, an optical pickup employs a laser diode (LD) to emit an optical beam through an optical element set to focus on the surface of the recording media. A photo detector integrated circuit (PDIC) is used for receiving the optical signal or detecting the strength of the optical signal.
FIG. 1 shows a schematic view of a conventional optical pickup. The optical pickup is used with a recording media 101 to read or write data to recording media 101. The optical pickup includes a photo detector integrated circuit (PDIC) 102, a laser diode (LD) 103, a polarized bean splitter 104, a quarter wave plate 105, a collimator lens 106 and an objective lens 107.
LD 103 emits a laser beam through polarized beam splitter 104, quarter wave plate 105, collimator lens 106 and objective lens 107 to focus on the surface of recording media 101. The laser beam is then reflected by the surface of recording media 101, through objective lens 107, collimator lens 106, quarter wave plate 105, and polarized beam splitter 104 to PDIC 102. PDIC 102 detects the strength of the laser signal. Polarization directions 109, 108, 110 indicate the polarization status of the emitting beams and the feedback beam, respectively.
The optical pickup may also use a plurality of optical lenses and polarized beam splitters to guide the emitting laser beam to recording media 101 and the reflecting beam to PDIC for reading or writing data.
Polarized beam splitter 104 is for transmitting and reflecting laser beam. Because of the material cost and the manufacture quality, polarized beam splitter 104 is a high-priced element in an optical pickup. In addition, quarter wave plate 105 also requires higher precision in a tedious manufacturing process, it is also an expensive element of the optical pickup.